The present invention relates to the general field of controlling clearance between the tips of rotary blades and a stationary ring assembly in a gas turbine.
A gas turbine, e.g. a high-pressure turbine of a turbomachine, typically comprises a plurality of stationary vanes disposed in alternation with a plurality of moving blades lying on the path of hot gas coming from the combustion chamber of the turbomachine. The moving blades of the turbine are surrounded around the entire circumference thereof by a stationary ring assembly. The stationary ring assembly defines the passage along which the hot gas flows through the blades of the turbine.
In order to increase the efficiency of such a turbine, it is known to reduce the clearance that exists between the tips of the moving blades of the turbine and the facing portions of the stationary ring assembly to a value that is as small as possible.
To achieve this, means have been devised that enable the diameter of the stationary ring assembly to be varied.
Nevertheless, that solution is found to be insufficient when the support to which the ring is secured also suffers thermal deformation around its circumference and in a manner that is not uniform, where such deformation has the effect of deforming the turbine ring.